A late-maturing navel orange. Discovered in Australia in 1950, fruit can be held on the tree for months fully ripe. In the ground it is a medium tree at 4-8m but can be grown in a large pot to keep 1.5-2m. Likes well drained fertile soil in a protected position in full sun.
The orange (specifically, the sweet orange) is the fruit of the citrus species Citrus ? sinensis in the family Rutaceae. The fruit of the Citrus sinensis is called sweet orange to distinguish it from that of the Citrus aurantium, the bitter orange. The orange is a hybrid, possibly between pomelo (Citrus maxima) and mandarin (Citrus reticulata), cultivated since ancient times.
Probably originating in Southeast Asia, oranges already were cultivated in China as far back as 2500 BC. Arabo-phone peoples popularized sour citrus and oranges in Europe and then, Spaniards introduced the sweet orange to the American continent in the mid-1500s.
Orange trees are widely grown in tropical and subtropical climates for their sweet fruit, which can be eaten fresh or processed to obtain juice, and for the fragrant peel. They have been the most cultivated tree fruit in the world since 1987.
Like most citrus plants, oranges do well under moderate temperatures?between 15.5 and 29 ?C ?and require considerable amounts of sunshine and water. It has been suggested that the use of water resources by the citrus industry in the Middle East is a contributing factor to the desiccation of the region. Another significant element in the full development of the fruit is the temperature variation between summer and winter and, between day and night. In cooler climates, oranges can be grown indoors.
As oranges are sensitive to frost, there are different methods to prevent frost damage to crops and trees when subfreezing temperatures are expected. A common process is to spray the trees with water so as to cover them with a thin layer of ice that will stay just at the freezing point, insulating them even if air temperatures drop far lower. This is because water continues to lose heat as long as the environment is colder than it is, and so the water turning to ice in the environment cannot damage the trees. This practice, however, offers protection only for a very short time. Another procedure is burning fuel oil in smudge pots put between the trees. These devices burn with a great deal of particulate emission, so condensation of water vapour on the particulate soot prevents condensation on plants and raises the air temperature very slightly. Smudge pots were developed for the first time after a disastrous freeze in Southern California in January 1913 destroyed a whole crop.